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Title: Covalency in Americium(III) Hexachloride

Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate. Consider the 60-year controversy sparked by SEABORG and COWORKERS (1954) when it was proposed that covalency from 5f-orbitals contributed to the unique behavior of americium in chloride matrixes. Herein, we describe the use of ligand K-edge X-ray absorption spectroscopy (XAS) and electronic structure calculations to quantify the extent of covalent bonding in – arguably – one of the most difficult systems to study, the Am–Cl interaction within AmCl 6 3-. We observed both 5fand 6d-orbital mixing with the Cl-3p orbitals; however, contributions from the 6d-orbitals were more substantial. Comparisons with the isoelectronic EuCl 6 3- indicated similar bonding for the Am III 6d- and Eu III 5d-orbitals. Meanwhile, the results confirmed SEABORG’S 1954 hypothesis that Am III 5f-orbital covalency was more substantial than 4forbital mixing formore » Eu III.« less
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Irvine, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0002-7863; TRN: US1702332
Grant/Contract Number:
AC52-06NA25396; AC05-06OR23100; SC0004739; AC02-76SF00515
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 25; Journal ID: ISSN 0002-7863
American Chemical Society (ACS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC). Nuclear Physics (NP) (SC-26); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Americium · Covalency · X-ray Absorption · Crystallography · Bonding · UV-Vis-NIR · Density Functional Theory · Spin-Orbit Coupling; Americium; Covalency; X-ray Absorption; Crystallography; Bonding; UV-Vis-NIR; Density Functional Theory; Spin-Orbit Coupling
OSTI Identifier: